Mackie M1200/M1400 owner manual Rack Mounting, Thermal Considerations, AC Power Considerations

GENERAL PRECAUTIONS AND CONSIDERATIONS

RACK MOUNTING

The M•1200/M•1400 amp requires two rack space units (2U = 3.5"). It also requires 16.25" depth inside the rack, including the rear sup- ports. When designing your rack, put the heavier items at the bottom and the lighter items toward the top.

Secure the front panel of the amplifier to the front of the rack using four screws with soft washers to prevent scratching the panel. In ad- dition, because of the weight of the amplifier, you must secure the rear support brackets of the amplifier to the back of the rack. You could use a support rail or shelf across the back of the rack, or angle brackets attached between the rear support brackets and the rear rails of the rack. This is recommended for all compo- nents mounted in a rack that is going to be moved frequently (or thrown in the back of a pickup truck and transported down a bumpy gravel road to that outdoor festival!).

THERMAL CONSIDERATIONS

The M•1200/M•1400 amps are fan-cooled and bring air in through the front and out through the sides. Make sure that cool air is available at the front of the amplifier, and that there is room on each side for the warm air to exit from the amplifier and dissipate. If rack- mounted, make sure there is room for the warm air to circulate around the side and out through the rear of the rack. In a typical rack, there will be a space of 1 to 2 inches on either side of the amplifier. This is adequate to allow the warm air to exit from the amplifier.

The M•1200/M•1400’s unique T-Design Constant Gradient Cooling Tunnel provides substantially better cooling for the output tran- sistors than conventional designs that simply blow air through the chassis, getting dust and other contaminants over all the internal components. The Cooling Tunnel provides a shorter, more directed path so the cool air con- centrates on the heat produced by the output devices. This results in increased reliability and longevity for the amplifier.

AC POWER CONSIDERATIONS

Be sure the M•1200/M•1400 is plugged into an outlet that is able to supply 120VAC at high current. If the voltage should drop below 116VAC, the M•1200/M•1400 will no longer be able to supply rated power. (It will continue to operate down to 50% of the rated voltage, but it just won’t be able to reach full rated power.)

Be sure the AC outlet can supply enough current to allow full power operation of all the amplifiers plugged into it. The outlet should be a three-prong socket that matches the power cord.

WARNING: Bypassing the plug’s ground pin can be dangerous. Please don’t do it.

The AC current demand of an amplifier var- ies depending on several factors, including the crest factor and the duty cycle of the program material. Under typical conditions reproducing rock music where musical peaks are just below clipping, the M•1200/M•1400 will require the following average currents:

	Average	Peak
	Current	Current
Amplifier Loading	Required	Required
2 ohms per side or 4 ohms bridged	8A	25A
4 ohms per side or 8 ohms bridged	5A	16A
8 ohms per side or 16 ohms bridged	3.2A	10A

It is recommended that a stiff supply of AC power be used because the amplifier places high current demands on the AC line. The more power that is available on the line, the louder the amplifier will play and the more peak output power will be available for cleaner, punchier bass.

Having said this, we also realize that in many applications a standard 15A service may be all that is available. Under typical condi- tions, reproducing rock music where musical peaks are just below the clipping point, you can safely connect more than one amplifier to a 15A service. Use the table below as a guide- line:

	Maximum Number
	of Amplifiers
Amplifier Loading	on a 15A Service
2 ohms per side or 4 ohms bridged	2
4 ohms per side or 8 ohms bridged	3
8 ohms per side or 16 ohms bridged	5

23